Manufacture of photographic gelatin relief images



United States Patent 3,129,097 MANUFACTURE OF PHOTOGRAPHIC GELATIN RELIEF IMAGES Albert Emiel van Hoof, Berchem-Antwerp, and Jozef Frans Willems, Wilrijk-Autwerp, Belgium, assignors t0 Gevaert Photo-Producten N.V., Mortsel-Antwerp, Belgium, a Belgian company No Drawing. Filed June 20, 1960, Ser. No. 37,101 Claims priority, application Belgium July 1, 1959 7 Claims. (Cl. 96-28) This invention relates to light-sensitive gelatino-silver halide emulsions for use in photography and particularly to unhardened gelatino-silver halide emulsions for use in photographic processes requiring the preparation of locally hardened or tanned silver halide emulsion layers.

Many silver halide developing agents are known, the oxidation products of which, produced in the photographic development process, possess the property of hardening gelatin emulsion layers in the region of exposure to light. The undeveloped and unhardened areas are removed with warm water and a gelatin relief image is obtained. The use of silver halide developing agents e.g. gelatin tanning silver halide developing agents, such as catechol or pyrogallol, in an alkaline medium, viz. potassium or sodium carbonate, potassium or sodium hydroxide, sodium triphosphate etc. suffer from the disadvantage that the gelatin which has not been hardened during the processing, has to be removed with warm water in order to obtain gelatin relief images. Very often this removal is rather difiicult viz. in those offices where a constant supply of warm water is hardly available egg. in an ofiice where matrixes are installed, as disclosed in the US. patent application Serial No. 582,944, filed May 7, 1956.

It has been proposed to avoid these difficulties by replacing the additional warm water treatment by an additional treatment of a solution of thiocyanate at room temperature. This process, however, always requires the use of a special bath for said additional treatment.

We have now found a method of producing a gelatin relief image by a simple treatment in a tanning developing bath which excludes the use of warm water or a special additional treatment.

Besides a tanning developing agent, an alkali and a development accelerator (hereinafter referred to as accelerator A or product A), this tanning developing bath contains also a softener for gelatin (hereinafter referred to as softener B or product B).

With an appropriate selection and dosage of the accelerator A and the softener B in the tanning developing bath, the tanning development is carried out in such a rapid way that the softening function of the product B definitely starts only after the tanning development has ceased If the products A and B are taken in inappropriate proportions, it might happen that product B effects its softening action so quickly and to such an extent as to prevent a sufiicient tanning development of the exposed areas of the light-sensitive material and thus there is always the risk of dissolving wholly or partly the tanned areas when the non-blackened and, consequently, unhardened areas are removed.

As product A, quaternary salts of organic nitrogen bases are especially appropriate, such as quaternary ammonium compounds, quaternary cyclic ammonium compounds, quaternary pyridinium (-quinolinium) compounds etc.

Also appropirate are polyonium salts having a quaternary ammonium-, a phosphoniumor a ternary sulfonium group which is linked to the onium-atom by an organic bivalent radical also linked to another onium group.

All these onium compounds can occasionally be substituted by other groups, excepting acid salt-forming groups or the salts thereof.

As examples may be mentioned:

Tetraethyl ammonium ethosulphate 1,4-dimethyl quinolium methosulphate Trimethyl lauryl ammonium chloride HaC CH3 I-(Z-hydroxyethyl)pyridinium chloride i C Hg 0 Hz 0 H 1- (methylcarb ohydrazide) -pyridinium chloride GET-C O-NH-NH;

N-p-nitrobenzylpyridinium chloride N-p-chlorobenzyl pyridinium chloride N-hexyl-N-p-nitrobenzyl morpholinium chloride 0 CHa N-(Z-methylbenzimidazolyl)-pyridinium chloride C-CH3 CHaSOF Ethylene dipyridinium-di-toluosulphonate [D Q zomQ-s or GH -C Trimethylene dipyridiniumdichloride C H:- CHr- C H: Pentamethylene dipyridiniumdichloride [3 Q 201- s a.

Trimethylene di-iso-quinoliniumdichloride Trimethylene-di-p-nitrobenzyl dipyrrolidinium dichloride These development accelerators can be employed in amounts of 0.5 to g./liter of developer-solution.

Among the product B compounds, the agents for softening the unhardened gelatin are urea, formamide, ethylene chlorhydrin, sodium salicylate, et cetera.

Excellent results are attained with urea. The amounts of urea necessary for the developing bath depend, among others, on the hardening degree of the silver halide emulsion layer, the time of development and the temperature. At room temperature (20 C.) 50 to 300 g. of urea per liter of developing bath are needed for rapid developing emulsions, and a time of development from 30 to 60 seconds is required. This amount may be increased at lower developing temperatures and reduced at high developing temperatures.

Besides the aforecited combinations of products A and B, also other photog'raphically active substances may be added to the tanning developing bath, such as anti-fogging agents, stabilizing agents preventing the air-oxidation of the tanning developer substance e.g. ascorbic borate, as described in our US. patent application Serial No. 758; 576, filed September 2, 1958.

When a photographic material, especially a paper support, is used for the manufacture of gelatin relief images according to the present invention, it is advantageous to apply to this support a silver halide emulsion layer containing percentages of urea amounting from 10 up to calculated on the dry gelatin.

The tanning developing agent can also be added to the light-sensitive silver halide emulsion layer itself. Then the development can be executed in an alkaline solution of the combination of products A and B together with other additions such as anti-fogging agents, wetting agents etc.

The process according to the present invention is not limited to the photographic processes for producing photographic gelatin relief images by the tanning development of an image-wise exposed gelatin silver halide emulsion layer. It can also be employed when the photographic gelatin relief images are obtained by the application of apparatus of the type used in the silver halide diffusion transfer process as described in US. patent specification No. 2,352,014.

For example, a hardened silver halide emulsion layer is coated onto an appropriate paper support. To this layer, an unhardened gelatin layer is applied, containing either developing and reducing nuclei or substances capable of forming such nuclei during the processing or even precipitating agents.

The exposure is followed by development in a tanning developing bath which contains besides the usual ingredients a development accelerator, a softener for gelatin and a silver halide solvent. The hardening developing agent can be present in the emulsion layer and/or in the receiving layer of the diifused silver halide, as well as in the developing bath itself.

The development can be carried out in any apparatus known in commercial practice and used for the application of the silver halide diffusion transfer process according to the afore-mentioned US. patent specification No. 2,352,014. Most of this apparatus has been described by I Bylemans in Progress in Photography 1955-4958, pages 31-33, entitled Image Transfer Processes.

It is evident that the new process can be applied to emulsion layers from which, after exposure and development, a positive image can immediately be obtained such as, e.g., direct positive emulsions, which have previously been treated with an appropriate amount of a fogging agent such as the silane compound described in British patent specification No. 821,251.

The following examples illustrate the present invention without limiting the scope thereof.

Example 1 A photographic paper sheet containing an unhardened silver chloride emulsion layer is exposed image-wise and then developed for 40 seconds at 20 C. in a developing bath of the following composition:

After leaving the bath, the photographic paper sheet is scoured with a rubber scraper to remove the undeveloped areas and a gelatin relief image is obtained.

Example 2 A photographic paper sheet containing an unhardened silver chloride emulsion layer is exposed image-wise and then developed for 40 seconds at 20 C. in a developing bath of the following composition:

G. Pyrogallol Sodium carbonate (anhydrous) Potassium bromide 0.01 Urea 200 Ascorbic borate-potassium salt 2 Ethylene dipyridinium dichloride 2 Water to l l.

The unhardened gelatin is removed by rinsing in Water at 20 C.

Example 3 A photographic paper sheet containing an unhardened silver chloride emulsion layer is exposed image-wise and then developed for seconds at 20 C. in a developing bath of the following composition:

The unhardened gelatin is removed by pressing the developed sheet on a sheet of ordinary paper. When the latter is stripped ofi, the unhardened gelatin sticks to this sheet of ordinary paper.

Example 4 A developing solution of the following composition is prepared:

G. Sodium carbonate (anhydrous) 30 Urea 30 Potassium sulphite 2 Ethylene dipyridinium dichloride l Catechol .8 Potassium bromide 0.08

The temperature of the solution is raised to 32 C. and the solution is poured out into an apparatus of the commercially available type, suitable for the reproduction according to the silver halide diffusion transfer process as described in the US. patent specification No. 2,352,014.

A paper sheet containing a light-sensitive silver halide emulsion is exposed image-wise. Next, this sheet and a sheet of ordinary paper are conveyed slowly through the aforesaid apparatus and, the papers are pressed together by the pressure rollers of the apparatus. The two adhering papers are separated by stripping off the piece of ordinary paper from the light-sensitive paper whereby the unhardened gelatin remains on the sheet of ordinary paper. On the exposed light-sensitive paper, a gelatin relief image is obtained.

Example 5 An unhardened silver halide emulsion of the direct positive type is coated onto a photographic paper support. After solidifying and drying, this material is exposed reflectographically to an original. Development is carried out as in Example 4.

We claim:

1. In a method of forming a photographic gelatin relief image, the steps of: treating an exposed gelatino silver halide emulsion with an aqueous composition comprising a developing agent that reduces the silver halide in the regions of the emulsion that have been exposed to light and is oxidized to a tanning agent that hardens the gelatin emulsion in these exposed regions; an organic onium salt that is, in the organic portion thereof, free from substituents selected from the group consisting of acid substituents and said acid substituents in salt form, said onium salt accelerating the actions of the developing and tanning agents, and a softening agent for softening the unexposed regions of the emulsion, the proportion of the amounts of onium salt and softening agent being such that the onium salt accelerates the actions of the developing and tanning agents on the exposed regions of the emulsion so that these regions are hardened prior to the action of the softening agent, and the softening agent thereafter selectively acts upon and softens the unexposed regions of the emulsion; and, removing thereafter the softened unexposed regions of the emulsion to produce a gelatin relief image.

2. In a method of forming a photographic gelatin relief image, the steps of: treating an exposed gelatino silver halide emulsion with an aqueous composition comprising a developing agent that reduces the silver halide in the regions of the emulsion that have been exposed to light and is oxidized to a tanning agent that hardens the gelatin emulsion in these exposed regions; an organic onium salt that is, in the organic portion thereof, free from substituents selected from the group consisting of acid substituents and said acid substituents in salt form, said onium salt being selected from the group consisting of quaternary ammonium, phosphonium, and sulfonium onium salts, said onium salt accelerating the actions of the developing and tanning agents, and a softening agent for softening the unexposed regions of the emulsion, the proportion of the amounts of onium salt and softening agent being such that the onium salt accelerates the actions of the developing and tanning agents on the exposed regions of the emulsion so that there regions are hardened prior to the action of the softening agent, and the softening agent thereafter selectively acts upon and softens the unexposed regions of the emulsion; and, removing thereafter the softened unexposed regions of the emulsion to produce a gelatin relief image.

3. In a method of forming a photographic gelatin relief image, the steps of: treating an exposed gelatino silver halide emulsion with an aqueous composition comprising a developing agent that reduces the silver halide in the regions of the emulsion that have been exposed to light and is oxidized to a tanning agent that hardens the gelatin emulsion in these exposed regions; a quaternary ammonium salt that is, in the organic portion thereof, free from substituents selected from the group consisting of acid substituents and said substituents in salt form, said quaternary ammonium salt accelerating the actions of the developing and tanning agents, and a softening agent for softening the unexposed regions of the emulsion, the proportion of the amounts of said quaternary ammonium salt and said softening agent being such that said quaternary ammonium salt accelerates the actions of the developing and tanning agents on the exposed regions of the emulsion so that these regions are hardened prior to the action of the softening agent, and the softening agent thereafter selectively acts upon and softens the unexposed regions of the emulsion; and, removing thereafter the softened unexposed regions of the emulsion to produce a gelatin relief image.

4. A bath for treating an exposed gelatino silver halide emulsion to develop and harden those regions of the emulsion that have been exposed to light and to soften the unexposed regions for subsequent physical removal, said bath comprising: a developing agent that reduces the silver halide in said exposed regions and is oxidized to a tanning agent that hardens the gelatin emulsion in said exposed regions; an organic onium salt that is, in the organic portion thereof, free from substituents selected from the group consisting of acid substituents and said substituents in salt form, said onium salt accelerating the actions of the developing and tanning agents on said exposed regions; and, a softening agent for softening the unexposed regions of the emulsion, said onium salt and said softening agent being resent in such proportion that the onium salt accelerates the actions of the developing and tanning agents on said exposed regions of the emulsion to develop and harden these regions prior to the action of the softening agent, and the softening agent thereafter selectively acts upon and softens the unexposed regions of the emulsion to prepare said unexposed regions for subsequent physical removal.

5. A bath for treating an exposed gelatino silver halide emulsion to develop and harden those regions of the emulsion that have been exposed to light and to soften the unexposed regions for subsequent physical removal, said bath comprising: a developing agent that reduces the silver halide in said exposed regions and is oxidized to a tanning agent that hardens the gelatin emulsion in said exposed regions; an organic onium salt that is, in the organic portion thereof, free from substituents selected from the group consisting of acid substituents and said substituents in salt form, said onium salt being selected from the group consisting of quaternary ammonium, phosphonium, and sulfonium onium salts, said onium salt accelerating the actions of the developing and tanning agents on said exposed regions; and, a softening agent for softening the unexposed regions of the emulsion, said onium salt and said softening agent being present in such proportion that the onium salt accelerates the actions of the develop ing and tanning agents on said exposed regions of the emulsion to develop and harden these regions prior to the action of the softening agent, and the softening agent thereafter selectively acts upon and softens the unexposed regions of the emulsion to prepare said unexposed regions for subsequent physical removal.

6. A bath for treating an exposed gelatino silver halide emulsion to develop and harden those regions of the emulsion that have been exposed to light and to soften the unexposed regions for subsequent physical removal, said bath comprising: a developing agent that reduces the silver halide in said exposed regions and is oxidized to a tanning agent that hardens the gelatin emulsion in said exposed regions; a quaternary ammonium salt that is, in the organic portion thereof, free from substituents selected from the group consisting of acid substituents and said substituents in salt form, said quaternary ammonium salt accelerating the actions of said developing and tanning agents on said exposed regions; and, a softening agent for softening the unexposed regions of the emulsion, said quaternary ammonium salt and softening agent being in such proportion that the quaternary ammonium salt accelerates the actions of the developing and tanning agents on said exposed regions of the emulsion to develop and harden these regions prior to the action of the softening agent, and the softening agent thereafter selectively acts upon and softens the unexposed regions of the emulsion to prepare said unexposed regions for subsequent physical removal.

7. A bath for treating an exposed gelatino silver halide emulsion to develop and harden those regions of the emulsion that have been exposed to light and to soften the unexposed regions for subsequent physical removal, said bath comprising: a developing agent that reduces the silver halide in said exposed regions and is oxidized to a tanning agent that hardens the gelatin emulsion in said exposed regions; a quaternary ammonium salt that is, in the organic portion thereof, free from substituents selected from the group consisting of acid substituents and said substituents in salt form, said quaternary ammonium salt having a concentration between about 0.5 and about 5.0 grams per litre of bath, said quaternary ammonium salt accelerating the actions of said developing and tanning agents on said exposed regions; and, urea for softening the unexposed regions of the emulsion, said urea having a concentration between about and about 300 grams per litre of bath, said quaternary ammonium salt and said urea being present in such proportion that the quaternary ammonium salt accelerates the actions of the developing and tanning agents on said exposed regions of the emulsion to develop and harden these regions prior to the action of the urea, and the urea thereafter selectively acts upon and softens the unexposed regions of the emulsion to prepare said unexposed regions for subsequent physical removal.

References Cited in the file of this patent UNITED STATES PATENTS 2,018,657 Bennett Oct. 29, 1935 2,197,809 McQueen Apr. 23, 1940 2,404,774 Dersch et al July 30, 1946 2,410,690 Smith et al Nov. 5, 1946 2,648,604 Welliver et al. Aug. 11, 1953 3,022,168 Stjarnkvist Feb. 20, 1962 FOREIGN PATENTS 566,314 Great Britain Dec. 21, 1944 OTHER REFERENCES Gladkides: Photographic Chemistry, vol. I, Fountain Press, England (1959), p. 55. (Copy in Sci. Libr.) 

1. IN A METHOD OF FORMING A PHOTOGRAPHIC GELATIN RELIEF IMAGE, THE STEPS OF: TREATING AN EXPOSED GELATINO SILVER HALIDE EMULSION WITH AN AQUEOUS COMPOSITION COMPRISING A DEVELOPING AGENT THAT REDUCES THE SILVER HALIDE IN THE REGION OF THE EMULSION THAT HAVE BEEN EXPOSED TO LIGHT AND IS OXIDIZED TO A TANNING AGENT THAT HARDENS THE GELATIN EMUSLION IN THESE EXPOSED REGIONS; AN ORGANIC ONIUM SALT THAT IS, IN THE ORGANIC PORTION THEREOF, FREE FROM SUBSTITUENTS SELECTED FROM THE GROUP CONSISTING OF ACID SUBSTITUENTS AND SAID ACID SUBSTITUENTS IN SALT FORM, SAID ONIUM SALT ACCELERATING THE ACTIONS OF THE DEVELOPING AND TANNING AGENTS, AND A SOFTENING AGENT FOR SOFTENING THE UNEXPOSED REGIONS OF THE EMULSION, THE PROPORTION OF THE AMOUNTS OF ONIUM SALT AND SOFTENING AGENT BEING SUCH THAT THE ONIUM SALT ACCELERATES THE ACTINS OF THE DEVELOPING AND TANNING AGENTS ON THE EXPOSED REGIONS OF THE EMULSION SO THAT THESE REGIONS ARE HARDENED PRIOR TO THE ACTION OF THE SOFTENING AGENT, AND THE SOFTENING AGENT THEREAFTER SELECTIVELY ACTS UPON AND SOFTENS THE UNEXPOSED REGIONS OF THE EMULSION; AND, REMOVING THEREAFTER THE SOFTENED UNEXPOSED REGIONS OF THE EMULSION TO PRODUCE A GELATIN RELIEF IMAGE. 